Doctors are reporting that the first set of stroke patients who took part in pioneering stem cell treatment trials have shown signs of improvement.
Six patients, who had human stem cells inserted close to the damaged part of their brain, have since witnessed improvements in the limb weakness that they suffered as a result of their stroke.
In one case, a man who underwent the treatment regained the power of speech after the stem cells of an aborted 12-week-old baby were injected into his brain.
However, doctors have cautioned against reading too much into the early results of the clinical trial, a world first for neural stem cell therapy for stroke victims.
The trial led by Glasgow University neurologist Professor Keith Muir, is being conducted at the Institute of Neurological Sciences at the Southern General Hospital in Glasgow.
"So far we've seen no evidence of any harmful effects. We're dealing with a group of people a long time after a stroke with significant disability and we don't really expect these patients to show any change over time," the Telegraph quoted Muir as telling the BBC.
"So it's interesting to see that in all the patients so far they have improved slightly over the course of their involvement in the study," he said.
The six patients had suffered strokes between six months and five years before they were treated, and all had been left with limb weakness.
The patients were assessed using the National Institutes of Health Stroke Scale, which ranked the first five patients with a median score of eight before the treatment and four points three months afterwards.
The sixth patient was treated less than three months ago. Six further patients will be treated as part of this Phase 1 trial.
Professor Muir said that he was "intrigued" by the early results of the research.
"We know that if you're involved in a trial you are going to see patients change in behaviour, particularly if you're doing something invasive, so we need to be very cautious indeed in interpreting these results," he said.
"However, that said, it is not something we'd anticipated seeing in this group of patients," he said.
Further trials are needed to establish whether stem cells actually help the brain repair damaged tissue.
Michael Hunt, chief executive officer of the company developing the treatment, ReNeuron, said that the clinical trial should be considered with caution at this stage.
"The clinical trial is primarily a safety study and we must therefore treat any of the observed early indications of functional benefit with considerable caution at this stage," he said.
"That said, we remain encouraged by the results seen in the study to date and we look forward to providing further updates," he added.